"The results of a tabulation are displayed on the clock-like dials. A sorter is on the right. On the tabletop below the dials are a Pantographic card punch (explained below) on left and the card reading station ("press") on the right, in which metal pins pass through the holes, making contact with little wells of mercury, completing an electrical circuit. All of these devices are fed manually, one card at a time, but the tabulator and sorter are electrically coupled" (http://www.columbia.edu/cu/computinghistory/census-tabulator.html).